Band saw with diamond abrasive teeth



May 25, 1943 E. VAN DER PYL 2,442,153

BAND SAW WITH DIAMOND ABRASIVE TEETH Filed April 23, 1946 Fig. 5

Fi g. 2

Elma/rm- EDWARD VAN DER PYL Patented May 25, 1948 PATENT OFFICE Norton Company, Worcester,-Mass., a corporation of Massachusetts Application April 23, 1946, Serial No. 864,370

4 Claims. (01. 125-21) The invention relates to a band saw for cutting very hard materials such as granite, marble and other hard stone.

One object of the invention is to provide a band saw for cutting extremely hard materials.

Another object of the invention is to provide a metal band with abrasive teeth which can flex as it passesover a pulley without disturbing the union between the band and the abrasive teeth.

Another object of the invention is to make arl0 ticles of the class indicated cheaply and expeditiously. Another object of the invention is to make a strong, rugged but flexible band saw having diamond abrasive teeth. Another object is to provide a band saw with a high cutting rate, lid

to shorten the time required for cutting stone blocks and the like. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements 2tand arrangements of parts, all as will be illustratively described herein, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings illustrating one 26 of many possible embodiments of the invention,

Figure 1 is an elevation of a fragment of a band saw constructed in accordance with the inven tion,

Figure 2 is a cross sectional view taken on the line 2-4 of Figure 1,

Figure 3 is a side elevation, on an enlarged scale, of an abrasive tooth,

Figure 4 is an end elevation of an abrasive tooth, on the same scale as Figure 3,

Figure 5 is a side elevation of the apparatus for welding or soldering the abrasive teeth onto the band, the loop being'broken away to show the nipples of the apparatus.

I provide diamond abrasive consisting of diamonds bonded with a non-ferrous metal bond. Preferably I proceed in accordance with my prior U. S. Patent Reissue No. 21,165, which describes the manufacture of diamond abrasives by mixing a quantity of crushed diamond bort with metal powder, pressing the mixture in a mold to make the desired shape, then sintering at a temperature high enough to form a strong, tough abrasive piece.

One widely used formula for diamond abrasive a successful bond is a mixture of copper, iron, tin and nickel in the proportion of 25% of each by weight in accordance with my Patent No. 2,238,351. Again the proportions may be varied widely. The size and concentration of the particles of crushed diamond may vary, depending upon the particular material to be ground, but as an illustrative example, I may use 25 per cent by i/"oluine of diamonds, the remainder metal powders, to form the bond.

Referring now to Figures 3 and .4, in accordance with the foregoing I mold and sinter a large quantity of diamond abrasive pieces iii which are of generally rectangular parallelopipedal shape having a longitudinal groove i i with right angles on one side.

Referring to Figures 1 and 2, I provide an endless steel band IE which can be placed over a pair of pullies, not shown, one or both being driving pullies in order that the band may be driven to cut a piece of granite, marble, or other stone. It is important that the steel band it shall be able to flex as it passes over the pullies without breaking the union between the metal bonded abrasive pieces it and the band H. To that end I provide at spaced intervals holes it in the steel band which may be of any desired shape although angles are to be avoided since they can set up detail fractures. To the same end I preferably provide curved cut-outs ill in one edge of the band it, the central points of which are preferably opposite the centers of the holes it.

The curved cut-outs i! leave lands or projections i8 therebetween upon which projections the diamond abrasive pieces in are secured in a manner which will now be described. Referring now to Figure *5, a disc wheel 20 is journalled on a threaded stud 2i projecting from a standard 22 uprising from a base 23. The disc wheel 20 has in its periphery a slot 24' which is just wide enough to receive and grip the steel band it. The back edge 25 of the steel band 15 is inserted in the slot 24 on the under side of the wheel. The foregoing constitutes means for indexing (moving spaced portions of the band to a fixed position) the steel band. The disc wheel 2|] is moved by hand and may be locked in any desired position by means of a wing nut 26 on the stud 2|.

I provide an induction heating and welding machine which will not be described in detail. Such machines are available on the market and I have obtained satisfactory results with a machine providing 1070 British thermal units per 55 minute, or approximately 20 kilowatts, at a freing copper pipes with coupling nuts for attaching the loops to the nipples 2|.

I select an open loop 33 which has a right angle bend, attach it to the nipples Iland locate the end of the loop 30 under the wheel 23 and spaced from the periphery of the wheel just far enough so that the loop extends around a land or pro- 2,442,rss I jection it. The loop can readily be bent downwardly a sufllcient distance to index the steel band II to bring successive lands l3 within it.

The base 23, which rests upon the bench 21, has another standard 3| upon which is pivotally mounted by means of astud 32, a lever 33. Pivotally mounted upon the right hand end of the lever 33 by means 01' a stud is a block 35 made of refractory insulating material. A weight 30 is attached to the left hand end of the lever 33. The weight 36 presses the block 35 upwardly. The grooves ll of the abrasive pieces 10 are slightly wider (of the order 01' .010 inch) than the thickness of the back 23 of the steel band.- I 5. I place a flat strip of solder onthe bottom of the groove ll of an abrasive piece ll, place the piece under and surrormding the land it which is within the loop 30 and then allow the block 3! to hold the parts together. The power is then turned on and the piece I. is soldered to the land I3. I then indexthe wheel 30 and attach another piece II to the next land II. In this way the steel band Ii is equipped with diamond abrasive teeth, one upon each land or proiec-g tion l3.

When the loop 30 is energized, the land or proiection l8 will heat up in a matter of seconds. Actually it will be red hot in about twenty seconds. It is kept at this for merely a few seconds and then the power is turned 01!. During this operation the solder melts andit not only wets the bottom of the groove II, but also runs up the sides thereof. Care should be exercised that no metal part shall touch the loop 30 as if it does aholewillbeburnedintheloop 30.

Although the land l3 inside of the diamond abrasive piece II gets red hot, the diamond abrasive piece II which is definitely in the high frequency electro-magnetic iield does not get red hot and in fact, remains comparatively cool. This is an important feature which enables me to make satisfactory piecesby this welding or soldering or brazing process since were the piece I. to "get red hot during the welding operation it would be ruined as an abrasive. The miter layer of diamonds in the piece ll would burn it it were red hot. r

There are two involved in induction heating. One is hysteresis and the other is eddy currents. Around every conductor electricity is a magnetic field. Ii the current is alternating, the magnetic ileld reverses with the alternation. A reversing magnetic field generates an electromotive torce in any conductor located in said field. Such an electrmnotive force will create eddy currents in a solid block of conducting material. On the other hand, if the material is etic, in addition to the eddy currents due to the conductivit of the material 4 there is the phenomenon of hysteresis, which constitutes the movement of the molecules of the material as they try to adjust themselves parallel to the magnetic lines of force which in this case change their direction 375,000 times a second.

Furthermore, the heating eii'ect due to the eddy currents is less with high conductivity material such as copper than it is with relatively poor conductors such as iron. For these reasons it is found that the lands it, being made of steel, can be heated red hot while the diamond abrasive piece "I, which is bonded with'a highly conductive, non-magnetic bond, is still relatively cold.

With regard to the solder, any hard solder or brazing material can be used and this includes various brasses and various formulae for silver solder. Merely as an example, I ilnd that a sll-' ver solder which consists of 55.82% Ag, 22.10% Cu, 17.19% Zn and 4.90% Sn, all parts by weight, gives 'very satisfactory results.

The pieces I when they are soldered or welded to the steel band I! are diamond abrasive teeth. It will be seen that the teeth .are wider than the band II and therefore they do all of the work,.and there is no binding of the band in the cut. The band saw is strong and the teeth are metallurgically attached to it so that it can absorb a great deal of power. Nevertheless, it readily flexes around the pulleys due to the holes it and the cut-outs 11. Band saws made in accordance with the invention will cut the hardest materials including granite and even harder stone and at a high cutting rate.

A feature of the invention is that the lands II are located in grooves ll of the teeth. This results in a metallurgical union on three faces of the grooves of the teeth and three faces of the steel band l5 so that it is practically impossible to break the union.

It will thus be seen that there has been provided by this inventiona band saw in which the various objects hereinbefore set forth together with many thoroughly practical advantages are successfully achieved.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth. it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:-

1. A band saw comprising a steel band having holes 'therethrough at spaced intervals and cutouts along one edge thereof opposite said spaced holes, and a plurality of metal bonded diamond abrasive teeth metallurgically attached to the same edge between the cut-outs.

2. A band saw according to claim 1 in which the teeth are wider than'the steel band.

3. A band saw according to claim 1 in which the bond for the abrasive teeth is non-ferrous metal and 01' greater conductivity than the steel of he band.

4. A band saw comprising a steel band having holes therethrough at spaced intervals and cut-' outs along one edge thereof leaving lands therebetween, the cut-outs being opposite the spaced holes, whereby the steel band will flex but not at the lands, and a plurality of grooved non-ferrous metal bonded diamond abrasive teeth the bond of which ismore conductive than the steel of the band, said teeth being metallurgically united to the lands on three feces of the lands UNi'rEn sums PATENTS Number Name Date 608,703 Murphy r Aug. 9, 1898 X 6 Name Date Ahearn May 4, 1915 Foerster Dec. 20, 1927 Jones July 5, 1932 Boyer Nov. 15, 1938 FOREIGN PATENTS Country Date Great Britain Apr. 10, 1917 Great Britain Oct. 3, 1932 

